The present invention relates to a disposable pull-on wearing article such as a disposable pull-on diaper or training pants.
Conventionally, disposable pull-on diapers are well known in the form of a disposable pull-on wearing article. In one example of well known pull-on diapers, a front waist region and a rear waist region are joined together along transversely opposite side edges thereof and these side edges may be torn apart to take the diaper off from the wearer's body. For example, Japanese Unexamined Patent Application Publication No. 1992-371146 (hereinafter referred to “REFERENCE 1”) discloses a disposable pant which can be used as the disposable pull-on diaper. In the case of the pant disclosed therein, a front waist region and a rear waist region are joined together along transversely opposite side edges thereof by use of a heat-sealing means. These side edges joined together in this manner have an appropriate strength such that the pant can be easily torn apart along these side edges to take the pant off from the wearer's body. In the pant, the front waist region and the rear waist region are respectively provided with a plurality of thread-like elastic members extending in the transverse direction of these waist regions and attached in a stretched state thereto while the crotch region is provided with a plurality of thread-like elastic members attached in a stretched state thereto so as extend along the peripheral edges of the respective leg-holes.
There has already been proposed also a pull-on wearing article including panels which are elastically stretchable in the direction of the waist line and interposed between a front waist region and a rear waist region. For example, National Publication of Translated Version No. 1996-507699 (hereinafter referred to “REFERENCE 2”) discloses a disposable pull-on diaper comprising an absorbent “chassis” and a pair of elastically stretchable “panels”. This diaper further comprises a waist-hole and a pair of the leg-holes. The “panels” which are elastically stretchable in the direction of the waist line are respectively provided in the vicinity of transversely opposite lateral regions of the wearer and attached to the “chassis” along predetermined joint lines. With this diaper put on the wearer's body, the “chassis” covers the front and rear waist regions as well as the crotch region of the wearer while the “panels” are elastically stretchable and contractible to make the diaper fit the lateral regions of the wearer's waist. When the diaper put on the wearer's body has been soiled with bodily discharges, the “panels” may be torn off from the “chassis” along the joint lines to take the diaper off from the wearer's body without the anxiety that the wearer's body might be soiled with bodily discharges.
The disposable diaper disclosed in Japanese Unexamined Patent Application Publication No. 1993-317356 (hereinafter referred to “REFERENCE 3”) is of pull-on type and a front waist region is provided along transversely opposite side edges with tear-apart lines used to tear the front waist region apart from a rear waist region. These tear-apart lines are in the form of intermittent slits or perforations (referred to as perforated lines) and extend in the vertical direction of the diaper across waist-surrounding elastic member and leg-surrounding elastic members. The diaper soiled with bodily discharges can be taken off from the wearer's body without anxiety that the wearer's body might be soiled with bodily discharges by tearing the front waist region apart from the rear waist region along the respective tear-apart lines.
Japanese Patent Publication No. 3421030 (hereinafter referred to “REFERENCE 4”) discloses a disposable undergarment provided with a tear-apart panel. The tear-apart panel defines a zone in which a front section and a rear section of the disposable undergarment can be torn apart from each other and continuously extends from one of the leg-holes to the waist-hole. The tear-apart panel comprises a strip of nonwoven material having no locally weakened part along which the strip can be easily torn apart with the bare hands. Preferably, this tear-apart panel has a transverse tensile strength in a range of 196.85 g/cm to 1968.50 g/cm, more preferably in a range of 787.40 g/cm to 1181.10 g/cm. According to an embodiment illustrated in this document, the tear-apart panel is adapted to connect the front section and the rear section of the undergarment and has its outer surface joined to respective outer surfaces of the front section and the rear section of the undergarment.
In the case of the pant disclosed in REFERENCE 1, each side edge of the front and rear waist regions comprises an inner sheet formed from a nonwoven fabric and an outer sheet formed from a lamination of plastic film and nonwoven fabric or the like. Assumed that the side edges of the front waist region each comprising a plurality of the sheet material layers are placed upon and joined to the side edges of the rear waist region by a heat-sealing means each of the side edges of the pant would comprise four to six sheet material layers heat sealed together. An effort to tear these side edges joined together apart one from another to take the pant off from the wearer's body may sometimes peel the nonwoven fabric and the plastic film off from each other just along the joined zones and properly disconnect the front and rear waist regions from each other. However, this will be rarely achieved and, in many cases, the front and rear waist regions of the pant will be disconnected from each other with the nonwoven fabric and the plastic film torn not along the joined zones but around the joined zones. In other words, the mother intending to take the pant off from the wearer's body must tear apart at least two or three layers of the sheet material at once with a considerable force. In addition to this inconvenience, it may be difficult for a caregiver of the wearer to achieve this operation quickly since it will be rare that these layers of the sheet material are rectilinearly torn apart. Assumed that the waist surrounding elastic members and the leg-surrounding elastic members are attached in a stretched state to the pant, respectively, these elastic members may be peeled off from the nonwoven fabric and the plastic film and thereupon intensely contract just as the side edges of the pants are torn apart. These elastic members peeled off in this manner may painfully hit against the fingertips of the caregiver.
The diaper disposed in REFERENCE 2 is said to ensure that the stretchable “panels” can be removed from the “chassis” along the joint lines of the “panels” and the “chassis”. However, on the assumption that these joint lines are formed by heat-sealing the stretchable “panels” with the “chassis”, operation of removing the “panels” from the “chassis” will really comprises, just like in the case of the pant disclosed in REFERENCE 1, operation of tearing the “panels” and/or the “chassis” along the joint lines. Such operation will require a considerable force and it may be difficult for the caregiver to achieve this operation quickly. Assumed that the stretchable “panels” include thread-like elastic members attached in a stretched state thereto, these elastic members intensely contract just as these “panels” are removed, and may painfully hit against the fingertips of the caregiver.
In the case of the diaper disclosed in REFERENCE 3, the tear-apart lines used to develop the diaper by tearing the front waist region apart from the rear waist region extend across the elastic members attached to the peripheries of the waist-hole and the leg-holes, respectively, by adhesive. With such arrangement, the elastic members may be severed or peeled off from the peripheries of the waist-hole and the leg-holes so as to be left contract, in any case, with the fingertips of the caregiver holding the diaper in order to develop the diaper. However, it is not easy for the caregiver to sever the elastic members and, even if possible, the elastic members may intensely contract upon being severed and painfully hit against the fingertips of the caregiver. This may occur also when the elastic members are peeled off from the peripheries of the waist-hole and the leg-holes, respectively, so as to be left contract.
The disposable undergarment disclosed in REFERENCE 4 specifies the transverse tensile strength of the nonwoven material used for the tear-apart panel adapted to be torn apart with the bare hands of the caregiver. However, when the pants-type wearing article is taken off from the wearer's body, it is usual to tear apart the transversely opposite lateral portions in the vertical direction and not usual to tear apart these lateral portions by pulling the wearing article. In other words, selection of the material for the tear-apart panels based on the transverse tensile strength is inappropriate to ensure that the wearing article can be easily or smoothly torn apart.